This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The proposed research will address a GAP IN KNOWLEDGE on specific markers for astrocytoma classification that can be used as prognostic and diagnostic markers of brain tumor aggressiveness. The proposed collaborative project will be carried out by an interdisciplinary team of researchers from basic and clinical sciences. Consequently, the objectives of the project, which centers on the broad topic of brain tumor research, are multi-pronged and involve the use of brain tumor samples from Puerto Rican individuals to perform genome-wide micro RNA (miRNA) expression arrays. In response to one of the main missions of the Puerto Rico Clinical and Translational Research Consortium (PRCTRC), which is to address health disparities among ethnic minority populations, this proposal will improve the participation of researchers of minority institutions in basic and translational cancer research. Astrocytoma, the tumor of astrocytic glial cells, is the most common type of central nervous system (CNS) neoplasms, accounting for more than 60% of all primary brain tumors. As histology-based classification is highly subjective, there is a need for more robust histologyindependent molecular classifiers. Although different gene expression and genome-wide array-CGH expression profiles have been use for classification, these expression signatures are yet to be translated to utility in clinical settings suggesting that these studies require further characterization and validation. Micro RNAs (miRNAs) are endogenous, short (19[unreadable]24 nucleotides) non-protein-coding RNAs that regulate gene expression at the post-transcriptional level. Alterations in the expression profiles of many miRNAs have been described in numerous human tumors. Recent evident indicate that the grade types of astrocytoma could be better classified by using a micro miRNA expression profiles compared with histological or gene expression analysis. In addition, short fragments of miRNAs are more stable compared with large messenger RNA (mRNAs) transcripts, which facilities their use. Although different studies have determined miRNA expression patters in different brain tumors, including malignant astrocytoma, miRNA expression signatures of astrocytoma according its malignant potential in Puerto Rican tumor samples have not been assessed. Thus, the OBJECTIVE of this research project is to construct a micro-RNA (miRNA) expression profile of astrocytoma according to its malignant potential in Puerto Rican brain tumor samples. This research is RELEVENT because this miRNA profile could be used for diagnostic, predictive and/or prognostic factor, as well as for therapeutic purposes. Our GENERAL HYPOTHESIS is that different miRNAs expression signatures are observed in astrocytoma samples according to its malignant potential (grade type) in Puerto Rican brain tumor samples. To test this hypothesis, we will pursue the following line of research: Specific Aim 1: To construct a micro-RNA (miRNA) expression profile of astrocytoma according to its malignant potential in Puerto Rican brain tumor samples.